i have a DB se5a with a zenoha 26 in it and flys fine now you say you have a 3w 20 this may do the job depending on the weight of the plane and the size of prop the 3w will turn.. Zenoah 26 on a carbon 18*8 is perfect so if a 3w can turn the same prop at 7800 -8000 rpm there should not be a problem